Percussion fuze with inertia type arming means



Oct. 6, 1964 c J LUNATl 3,151,558

PERCUSSION FUZE WITH INERTIA TYPE ARMING MEANS Filed Aug. l. 1961 n l A United States Patent O 3,151,558 PERCUSSIUN FUZE WITH RTIA TYPE ARMING MEANS Charles Joseph Lunati, Montrouge, Seine, France, assignor to Etat Francais, represented hy the Ministerial Delegate for Armament, Paris, France Filed Aug. 1, 1961, Ser. No. 128,501 Claims priority, application France Aug. 8, 1960 8 Claims. (Cl. 102-78) The present invention relates to a percussion fuze adapted to prime the explosive head of a rocket, rotating or not about its axis, fired from a tube either for airground or ground-ground purposes.

It is known that for projectiles adapted to explode on Contact with the ground the following qualities are especially desirable: instantaneous explosion, up to the largest angles of incidence at impact; maximum spacing of the explosive part of the rocket from the ground at impact.

To these tactical considerations the usual safety requirements before use have to be added, viz: safety in storage, transportation, handling and accidental falling, together with interruption in the ring chain.

Finally, additional qualities in use, arising from launching conditions may be required: impossibility for the fuze to become armed While the rocket is travelling through the launching tube; necessity for the fuze to remain inert during the unloading of a rocket jammed in the tube after tiring; impossibility of exploding before reaching a safe distance from the muzzle of the launching tube; safety in unloading unred rockets; safety in respect of the aircraft in the event of a crash-landing, throwing earth over the rocket fuze; facility in rendering safe and disposing of unexploded rockets with safety.

All of the features required must naturally be catered for with minimum cost.

The object of the present invention is to provide a fuze fulfilling as far as possible the aforesaid conditions.

The instantaneous mechanical percussion fuze according to the invention is elongated, having a cylindrical base of diameter equal to the caliber of the explosive head of the rocket and has a mechanism which is armed by the force of set-back resulting from propulsion. It is particularly characterised by a mechanism which comprises the combination of an elongated striker lying along the longitudinal axis of said fuze, locking means adapted to immobilise said striker in its safe position, a primer borne by a transversal slide situated in the cylindrical base of said fuze, the primer being held out of alignment with the longitudinal axis of said striker in said safe position, said slide abutting and compressing a spring at one side thereof and bearing an offset pin on the opposite side thereof adapted to abut the inner wall of a launching tube when said fuze of said rocket is within said launching tube, means for immobilising said slide by said striker when said striker is in its aforesaid safe position, unlocking means adapted to free said locking means only when said fuze passes the muzzle of said launching tube after tiring, and a safety lock adapted to immobilise said unlocking means and said pin when said fuze is to be made safe.

Advantageously the mechanism is mounted in an assembly comprising a metallic base portion and a tubular metallic core portion, said assembly being surrounded by plastic material Crilsan or nylon moulded thereon to yconform to the nal desired elongated shape of said fuze to thereby constitute a plastic fairing, said striker projecting beyond the fore extremity of said core portion when said fuze is primed.

Other features and advantages of the invention will become clear from the following detailed description of one preferred embodiment thereof, with reference to the figures in the accompanying drawings.

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FIGURE l is a section along the longitudinal axis of a fuze according to the preferred embodiment of the invention mounted on the explosive head of a rocket.

FIGURE 2 is a detail in elevation of the safety lock litted to the fuze of FIGURE l viewed in the direction of arrows II-II on FIGURE 1.

The fuze is made of a suitable plastic material moulded over a metallic assembly which contains a tubular core portion and a base portion which houses the fuze mechamsm.

The fuze is of a very elongated shape and constitutes the entire conical head of the projectile; its base has a diameter equal to the caliber of the explosive head of the rocket (or the internal diameter of the tube); accordingly the explosive head (shown in the drawing) is cylindrical and therefore economic. The head 1a of the striker 1, when the fuze is armed, projects from the metallic forepart of the fuze into a nose-piece 2 of transparent plastic material. The amount of such projection is limited by a keeper 1b.

The primer 3 is located in a cylindrical slide 4, transversely situated in the cylindrical base of the fuze; when it is in the safe position, the primer 3 is not in alignment either with the channel leading to the explosive charge or with the striker 1. Accordingly the latter cannot reach the primer when in this safe position.

The pin 4a, which is offset for orientation purposes, i.e. to prevent rotation of the slide, forms an extension of the slide 4, said pin extending through the fuze wall bears against the inner wall of the launching tube. A spring 4b biases the slide 4 to its operative position.

When the fuze is in storage the slide 4, immobilised by the tip of the striker 1 extending thereinto by way of a recessed hole, can also be locked from the outside by means of a safety lock 5 remaining in place on the fuze during the lire and movable between two positions: S (safety) and F (lire). In position S, the lock grips and immobilises the pin 4a.

Prior to firing, the striker 1 is immobilised in the central metallic core portion of the fuze by means of balls 6. These balls are retained in position by a sleeve member 7 capable of retracting against the opposition of a standardised spring 7 a When under the effect of launching acceleration. The standardisation of spring 7a and the course of the sleeve member 7 are calculated to ensure that the balls do not become freed in the event of the rocket falling on its aft end. This sleeve member 7 is not adjusted in its center on the striker 1; the striker 1 passes into a large hole without any adjustment.

In order to free the balls, the sleeve member 7 has to retract until it seats on the bottom 7b of the bore in which it is movable. It is prevented from completing its full travel by a bolt S-Sb held, despite a return spring 8a, with its head 8 projecting into the bore, the shank 8b of said bolt bearing against the inner wall of the launching tube. Thus, full retraction of the sleeve member 7 is prevented either as long as the fuze is within the launching tube or as long as the safety lock is in the position S.

The function of .the fuze is as follows: on positioning the rocket in i-ts launching tube 10, the safety lock 5 is changed manually from S to F. Both the pin 4a and the shank 8b are then liberated; on firing, the rocket starts to accelerate and the mobile members tend to move to the rear on the effect of set-back force. The striker 1 abuts against the keeper 1b, the sleeve member 7 retracts in compressing the compression spring 7a, but is stopped on contacting the bolt head 8, the shank 8b of which is in frictional engagement with the launching tube. Due to the fact that the rearward travel of sleeve member 7 has been stopped, the balls 6 are not released and the striker 1 remains locked.

It will be seen in passing that should the rocket be stopped in the launching tube for any reason (wedging, bursting of the rocket propellant, etc.), the acceleration ceases; then the sleeve member 7 returns to its safe position under the action of its spring 7a and the fuze remains inert as it was before firing and without any modification in the position of its components.

With the propulsion (hence acceleration) of the rocket continuing outside the tube, the sleeve member 7 is able to retract completely, until it seats on the bottom 7b of its bore, entirely freeing itself from the head la of the striker and Ithus releasing the balls 6, as long as the bolt 8 is no longer restrained by the launching tube. Machining of the bolt head 8 to taper in part advantageously promotes the displacement of said bolt under the effect of the sleeve member 7 bearing thereon.

Meanwhile, -the acceleration maintains the striker, by the effect of set-back force, in its safe position although the balls 6 are no longer held in place. As soon as propulsion (hence acceleration) ceases, the sleeve member 7, which had completely left the head la of the striker, returns forward under the action of its spring 7a. It cannot re-enter this head 1a for lack of centering because it is not adjusted on the striker 1 and accordingly, it pushes the striker forward until the head 1a abuts the keeper 1b. The striker 1 leaves the recessed hole provided in the slide 4. This transporter, pushed by its spring 4b, goes to the other side of its housing, thus aligning the primer 3 with both the channel leading to the explosive charge and the percussion tip of the striker 1. The fuze is only then armed, being at a substantial distance from the muzzle of the launching tube.

Due to the head la of the striker being advanced into the nose-piece 2, percussion on impact is possible at larger angles of incidence.

The fuze disclosed facilitates unloading of unfired rockets; since such unloading requires the rocket to be extracted from the rear backwards, it will be appreciated that the safety lock becomes visible to the operator before the pin 4a and the shank Sb which are still engaged within the launching tube. It is therefore an easy matter to push the safety lock 5 from F to S before replacing the rocket under its safe storage conditions. This feature is of particular importance when unloading a damaged rocket-launcher, such as may be required in the case of a crash-landed aircraft where earth has been violently thrown into the launching tubes. This projected earth hitting the nose of the fuze cannot cause this fuse to be actuated in view of the offset position of the primer relative to the striker.

An armed fuze is readily recognizable since its striker head 1a is visible through the nose-piece 2 and at the same time the pin 4a is seen to project laterally from the body of the fuze.

When clearing target areas of unexploded rockets, those fuzes which have failed to function on impact (for instance following a dead flat landing by the rocket through failure of its stabilising fins) can be returned to safe by pushing the pin da back into the fuze and putting the safety lock 5 to its S position.

Although the present invention has been described in conjunction with a preferred embodiment it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

I claim:

1. Instantaneous mechanical percussion fuze for a rocket launched by means of a launching tube, said fuze comprising a combination of (a) a percussion mechanism functioning under the action of acceleration forces caused by the propulsion 4 of the rocket, having an elongated striker situated in a longitudinal axis of said fuze,

(b) a first locking device immobilizing the striker including (c) a tubular member surrounding said striker movable toward its unlocking position upon initial launching movement of the fuze in the launching tube,

(d) resilient means for causing said tubular member to resume its initial safe position and its ini-tial state when the fuze is accidentally stopped in the said launching tube,

(e) a second locking device comprising a shank of which one extremity engages the inner wall of the launching tube when the fuze is in the tube and the other extremity is held disposed in the path of movement of the tubular member by the engagement of said one extremity with the inner wall of the launching tube to prevent the said member of the first locking device from moving to its fully unlocking position for freeing the striker,

(f) a cylindrical slide mounted for transverse sliding movement in the fuze having a receiving hole therein for housing the tip of the striker,

(g) a primer carried by said slide,

(h) a guide member for the slide extending from one end of said slide and flush with the inner wall of said tube when the fuze is in the tube,

(i) means engaging the other end of said slide to urge the slide to a position in which the primer is disposed in the path of movement of the striker when the tip of the striker is no longer housed in said receiving hole and the fuze is launched from the tube, and

(j) means acting on said shank, when 'the fuze is launched from the tube, to withdraw the shank from the path of movement of the said member of the first locking device to permit said first locking device member to move to its unlocking position to free the striker for the detonating stroke.

2. A percussion fuze as claimed in claim 1 further comprising (j) a conical-shaped frame comprising (k) a metallic base, and

(l) a hollow elongated conical head having a central hollow elongated metallic tube therein coaxial with the fuze,

(m) said base having a diameter substantially equal to the caliber of the explosive head of the rocket and adapted to be mounted thereon,

(n) said frame being surrounded by plastic material shaped to give the fuze the desired form,

(o) the percussion mechanism and the first locking device being lodged within said hollow tube, and

(p) the second locking device and the slide being lodged in said base.

3. Instantaneous mechanical percussion fuze for a rocket according to claim 2, wherein the fore extremity of said fuze is transparent thereby enabling the striker head to be observed when the striker is armed.

4. Instantaneous mechanical percussion fuze for a according to claim 2, wherein (s) the striker is an elongated rod situated in the axis of the hollow tube having a head at one end provided with a recess and having a skirt and having a tip at the other end,

(t) a keeper carried by the elongated central tube and extending into said recess in the striker head to limit displacement of the striker, said first movable locking member comprising (u) a sleeve member for sliding in said striker skirt within the elongated hollow central tube and having a fore aperture through which said striker rod extends and the diameter of which is larger than that of the striker rod, the said skirt having (v) a plurality of apertures at the same level,

(w) the length of the sleeve member being less than the distance between the lower edge of the skirt and the bottom of the central tube, the wall of the central tube having (x) a plurality of apertures in correspondence with said apertures in said skirt when the head of the striker is in contact with the front of the sleeve member,

(y) a plurality of balls, each of said apertures in the wall of the central tube acting in cooperation with its associated one of said apertures in said skirt to provide a housing for one of said balls, said balls, in association with said sleeve member, said skirt and said central tube, constituting said rst locking device for the striker, said sleeve member upon initial launching of the fuze and rocket and due to the set-back force generated by the acceleration of the rocket, moves to its fully unlocking position in which the sleeve member frees the balls and the striker, said sleeve member when in its fully unlocked position will be entirely clear of the striker skirt and due to the difference in diameter of the striker rod and the fore aperture of the sleeve member the striker rod and the sleeve member become olf-centered so that upon outward movement of the sleeve member, it will engage the striker skirt and move the striker rod outwardly to move the tip of the striker rod out of the recess in the slide, and

(z) resilient means between the bottom of the central tube and the front of the sleeve member to move the sleeve member outwardly.

5. Instantaneous mechanical percussion fuze for a rocket according to claim 4, wherein said base of the fuze has (s) an opening therethrough, said second locking device for the striker comprises (t) a bolt including a head and said shank extending through said opening in said base to engage the inner wall of the launching tube so that the head of the bolt projects into the central tube into the path of inward movement of said sleeve member to prevent said rst sleeve member from reaching its fully unlocking position while the fuze is in the launching tube, the distance between the ball housings and the bolt head being less than the length of the sleeve member, and

(u) resilient means located between the bolt head and a part of the lateral wall of the base to withdraw the bolt head from the path of movement of the sleeve member when the fuze is launched from the launching tube to permit the sleeve member to reach its fully unlocked position to free the balls and permit the striker to strike the detonation blow upon contact of the fuze with an object.

6. Instantaneous mechanical percussion fuze according to claim 5, wherein the end of the bolt head is frustoconical.

7. Instantaneous mechanical percussion fuze for a rocket, according to claim 5, wherein the guide member for the said cylindrical slide is fixed to said cylindrical slide at a point remote from the axis of said cylindrical slide, said guide member being itself guided by an aperture in the lateral Wall of the base of the fuze, the free end of said guide member being flush with the inner wall of the launching tube.

8. Instantaneous mechanical percussion fuze for a rocket according to claim 7, wherein said base has a recess provided in its outer surface to receive the free ends of said guide member and the shank of said bolt, said fuze further comprises (s) a safety lock on the outer surface of the fuze for said guide member and bolt including (sl) a plate housed to slide in said recess and containing two similarly shaped and oriented openings each of which comprises two profiles in plan,

(s2) the lirst profile being adapted to allow said free end to pass freely therethrough and (s3) the second profile being adapted to grip said free end so that, in one extreme position of said plate, Said two first proiiles are aligned with said guide member and said shank respectively, and when said plate is slid in said recess to its other extreme position said two second profiles are aligned with said guide member and said shank respectively which are thereby prevented from moving outwards from the fuze.

References Cited in the le of this patent UNITED STATES PATENTS 2,705,921 Moseman Apr. l2, 1955 2,870,713 Saloranta et al. Ian. 27, 1959 FOREIGN PATENTS 336,727 Switzerland Apr. 15, 1959v 

1. INSTANTANEOUS MECHANICAL PERCUSSION FUZE FOR A ROCKET LAUNCHED BY MEANS OF A LAUNCHING TUBE, SAID FUZE COMPRISING A COMBINATION OF (A) A PERCUSSION MECHANISM FUNCTIONING UNDER THE ACTION OF ACCELERATION FORCES CAUSED BY THE PROPULSION OF THE ROCKET, HAVING AN ELONGATED STRIKER SITUATED IN A LONGITUDINAL AXIS OF SAID FUZE, (B) A FIRST LOCKING DEVICE IMMOBILIZING THE STRIKER INCLUDING (C) A TUBULAR MEMBER SURROUNDING SAID STRIKER MOVABLE TOWARD ITS UNLOCKING POSITION UPON INITIAL LAUNCHING MOVEMENT OF THE FUZE IN THE LAUNCHING TUBE, (D) RESILIENT MEANS FOR CAUSING SAID TUBULAR MEMBER TO RESUME ITS INITIAL SAFE POSITION AND ITS INITIAL STATE WHEN THE FUZE IS ACCIDENTALLY STOPPED IN THE SAID LAUNCHING TUBE, (E) A SECOND LOCKING DEVICE COMPRISING A SHANK OF WHICH ONE EXTREMITY ENGAGES THE INNER WALL OF THE LAUNCHING TUBE WHEN THE FUZE IS IN THE TUBE AND THE OTHER EXTREMITY IS HELD DISPOSED IN THE PATH OF MOVEMENT OF THE TUBULAR MEMBER BY THE ENGAGEMENT OF SAID ONE EXTREMITY WITH THE INNER WALL OF THE LAUNCHING TUBE TO PREVENT THE SAID MEMBER OF THE FIRST LOCK- 